IPA: /ɪnˈdɪvɪzəbli/
KK: /ɪnˈdɪvɪzəbli/
In a way that cannot be divided or separated.
The two countries are indivisibly linked by their shared history.
Indivisibly → It is formed from "in-" (meaning not) and "divisus" (from "dividere", meaning to divide) and the suffix "-ly" (meaning in a manner). The word "indivisibly" means in a manner that cannot be divided or separated.
Think of 'not' ('in-') being able to 'divide' ('dividere') something — that's why indivisibly means something that cannot be divided.